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1.
传统的正关联规则主要考虑事务中所列举的项目,负关联规则不仅要考虑事务中所包含的项目,还要考虑事务中所不包含的项目,它包含了非常有价值的信息。本文对负关联规则的相关定义、支持度及置信度的计算方法进行了分析讨论,并讨论了对负关联规则挖掘中出现的矛盾规则问题及利用规则相关性解决矛盾规则问题,最后给出了其挖掘算法及其实现。  相似文献   

2.
传统的关联规则只关注于挖掘出项集间的正关联规则,但在实际应用中负关联规则同样隐含着有价值的信息.本文首先给出了正、负关联规则的定义及支持度和置信度的函数表示,重点分析了关联规则中"支持度—置信度"架构的局限性,提出了利用项集的相关性来解决关联规则中正、负矛盾规则出现的问题,同时针对置信度的设置进行了研究分析,最后对负关联规则挖掘的算法进行了讨论,旨在为关联规则的研究奠定基础.  相似文献   

3.
现有关联规则挖掘算法都是在频繁项集基础上进行挖掘,关于非频繁项集的资料很少.特别是在研究负关联规则后,非频繁项集因包含重要的负关联规则而变得非常重要.针对这一问题,在多支持度算法的基础上提出了一种新的算法模型,能够在挖掘频繁项集的同时得到非频繁项集,实验结果表明了该算法的有效性.  相似文献   

4.
针对仅有的挖掘算法不能较好地解决负关联规则的候选集数量爆炸问题,为满足用户的实际需求,提出带约束负关联规则概念,建立带约束负关联规则挖掘算法CNARM.同时,在挖掘过程中,利用最大频繁模式的性质来生成候选集,通过限制负关联规则中的前后件项目个数和利用负关联规则的性质来缩小候选集的规模.理论分析和实验结果表明本文提出的算法是有效可行的,具有较好的挖掘效率.  相似文献   

5.
一种改进的负关联规则挖掘算法   总被引:6,自引:0,他引:6  
负关联规则A→—B(或者-A→B,-A→B)描述的是项目之间的互斥关系,其与传统的关联规则有着同样重要的作用.然而,负关联规则和传统正关联规则的挖掘有很大不同,因为负关联规则隐藏在数量巨大的非频繁项集中.因此提出一种新的挖掘horn子句类型负关联规则的算法,并且实验证明是行之有效的.  相似文献   

6.
基于相关系数的正、负关联规则挖掘算法   总被引:2,自引:0,他引:2  
负关联规则描述的是项目之间的互斥关系,它与传统的正关联规则有着同样重要的作用。然而,大多规则挖掘算法只能挖掘正规则而忽略了负规则的挖掘。本文利用统计学中相关系数的理论,提出一个能同时挖掘正、负关联规则的算法,实验表明该算法是有效的。  相似文献   

7.
为了解决负关联规则挖掘中包含负项目的频繁项集数量爆炸问题,引入过频繁项集的概念,证明过频繁项集及其所有超集均不可能产生有趣的关联规则。在频繁项集生成过程中,必须对项集中包含负项目的个数进行限制。使用最小支持度、最大支持度、项集中最多包含负项目的个数2个参数来约束频繁项集生成过程的算法。实验结果表明:所增加的两个参数是必要的,特别是当数据集中所包含的项目个数比较多时,只有恰当地设置两个额外参数,才能够保证挖掘过程的正常进行。  相似文献   

8.
负关联规则挖掘中的频繁项集爆炸问题   总被引:4,自引:0,他引:4  
为了解决负关联规则挖掘中包含负项目的频繁项集数量爆炸问题,引入过频繁项集的概念,证明过频繁项集及其所有超集均不可能产生有趣的关联规则。在频繁项集生成过程中,必须对项集中包含负项目的个数进行限制。使用最小支持度、最大支持度、项集中最多包含负项目的个数2个参数来约束频繁项集生成过程的算法。实验结果表明:所增加的2个参数是必要的,特别是当数据集中所包含的项目个数比较多时,只有恰当地设置2个额外参数,才能够保证挖掘过程的正常进行。  相似文献   

9.
关联规则挖掘算法研究   总被引:1,自引:0,他引:1  
详细研究了关联规则数据挖掘,分析了存在的问题和不足,提出了一种频繁项集增量算法,用于对Apriori算法进行改进.实验表明,改进算法在运行效率上要比Apriori算法快一个数量级.  相似文献   

10.
快速关联规则挖掘算法   总被引:1,自引:0,他引:1  
刘景春 《佳木斯大学学报》2004,22(2):151-156,177
提出了一种新颖的关联规则挖掘算法QAIS,与经典两阶段式关联规则挖掘算法不同的是,它只需扫描一遍事务数据库,不需要生成候选集,并且可以方便的应用在增量式关联规则挖掘算法中,该算法经合成数据验证是有效的.同时针对关联规则生成过程中出现大量冗余规则的问题,还讨论了冗余关联规则去除的问题.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

14.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

15.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

16.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

17.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

18.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

19.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

20.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

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